1. Field of the Invention
The present invention relates to improvement in a photo-solidification modeling method and a photo-solidified object fabricated by the method.
2. Description of the Prior Art
There has been proposed a photo-solidification modeling method for embodying a three-dimensional shape which is defined by a three-dimensional data designed by a three-dimensional CAD or the like. The photo-solidification modeling method is useful for embodying the three-dimensional shape which is defined in data but not embodied yet in an actual shape. The summary of the photo-solidification modeling method is disclosed in Rev. Sci. Instrum. Vol.52(11) November 1981, p.1770-1773.
In order to reduce the required time of the photo-solidification modeling method or to use the solidified method as a casting model, there has been proposed an improved technique of fabricating a hollow object (which may be referred to as a superficial model) by exposing a liquid photo-solidifying resin to a light only at a region corresponding to a desired contour or outer surface of a desired shape. In order to increase the strength of the superficial model or prevent distortion thereof, there has been also proposed a technique of fabricating a solidified object having a superficial skin with a honeycomb structure formed therein. These improved techniques are disclosed in Japanese Laid-Open Patent Publication No. 4-118222 filed by the assignee of the present invention.
The technique disclosed in the above prior art publication uses a control system in which the space within the contour is spacedly exposed to a light so as to form a lattice of ribs within the superficial model.
When such a honeycomb structure is formed within the superficial model in accordance with the prior art, the space in the model is divided into a plurality of cells by the lattice of ribs of the honeycomb structure. When the ribs are arranged in a lattice, for example, in section taken in an X-Y plane of a three dimensional space (herein defined by X, Y and Z), extending uniformly in the Z direction, each of the cells defined by the ribs is of a square prism. Alternatively, if the ribs are arranged in a honeycomb in section taken in the X-Y plane, extending uniformly in the Z direction, each of the cells defined by the ribs is of a hexagonal prism. Further, if the ribs are arranged in a lattice in a section taken in any of the X-Y, Y-Z and Z-Y planes, each of the cells defined by the ribs is cubic.
Thus, the superficial model is reinforced by the ribs from inside thereof, assuring provision of a strong object with little distortion. Furthermore, the object of this construction is effective to reduce the fabricating time and the amount of a resin used for modeling in comparison with a solid model.
Though the superficial model with a honeycomb structure formed therein is advantageous as described above, it is accompanied with a problem that, as there is no communication among the cells defined by the ribs, the unsolidified liquid in the cells is confined therein and difficult to be ejected therefrom. In the known technique, such unsolidified liquid in the cells is individually ejected through small holes formed in the outer surfaces defining the respective cells, which requires a troublesome work and which is not so effective as to satisfactorily eject such unsolidified liquid. As the result, the amount of the resin used for modeling cannot be reduced so much as expected, and the unsolidified liquid not ejected from the cells will have an adverse effect when the solidified object is used as a casting model.